Tuatara

Tuatara eat beetles, worms and big insects called wētā.

Sometimes they eat seabird eggs and chicks, or small lizards.

Tuatara are hunters that mostly eat invertebrates: beetles, wētā (big New Zealand insects related to crickets), worms, millipedes and spiders. They also eat lizards, and seabird eggs and chicks.

Tuatara have a slow body, so they do not need to eat as often as most other reptiles. They are most active at night.

The diet is mainly invertebrates, including beetles, wētā, worms and millipedes, with the rest made up of lizards, seabird eggs and chicks, and occasionally young tuatara (Department of Conservation); Animal Diversity Web adds snails, frogs and small birds. Because its metabolic rate is very low, the tuatara feeds less often than most other reptiles.

Rats harm tuatara partly through competition: DOC notes that rats compete for the same invertebrate food, and that islands with rats have few nocturnal invertebrates or reptiles.

Tuatara sleep in burrows in the daytime.

At night they come out to hunt. Boy tuatara raise their spiky crests to look big.

Tuatara are most active at night. Each tuatara usually lives alone in a burrow, which it sometimes defends. On sunny days, they may sit at the burrow entrance to soak up some warmth, and when it is cold they stay inside.

Male tuatara show off by puffing up their bodies, raising their crests and darkening the skin around their necks. They do this to challenge other males and to approach females.

Tuatara are nocturnal and solitary, living singly in burrows they sometimes defend, and basking at the entrance on sunny days (Animal Diversity Web). In cold weather they stay in their burrows.

In male contests and courtship, males inflate the body, raise the crest and darken the skin between the shoulders and the neck crest. Copulation is by cloacal contact, as males have no external sex organs.

Rats that people brought to New Zealand ate tuatara eggs and babies.

Now people keep the tuatara's islands free of rats. Tuatara are protected by law.

When people arrived in New Zealand, they brought rats. Rats eat tuatara eggs and babies and eat the insects tuatara need. Tuatara breed so slowly that they cannot keep up, so they disappeared from the mainland and from some islands.

Today rats have been removed from almost every island where tuatara live, and tuatara have been moved to more rat-free islands and fenced sanctuaries. Tuatara were protected by law in 1895. Visitors help by following the no-landing rule on tuatara islands and checking their gear for pests.

The IUCN lists the tuatara as Least Concern (assessed and published 2019), with more than 55,000 mature individuals, but stresses that it is entirely reliant on conservation management to keep invasive species off its islands. New Zealand's own threat classification lists it as At Risk, Relict (Department of Conservation). Introduced rats, including kiore, are thought to have caused much of the past decline by preying on eggs and hatchlings and competing for food, and rats have now been eradicated from all but one island with a known population.

Other concerns include habitat change (more than 80 percent of Stephens Island's forest was cleared for farms by the 1920s), low genetic diversity in small or once-reduced populations, and illegal collecting. The tuatara was legally protected in 1895, one of New Zealand's first protected native species, and is listed on CITES Appendix I.

Scientists study tuatara to learn about animals from long ago.

In 2020 scientists read the tuatara's genes, the instructions inside its body.

Some scientists call the tuatara a "living fossil". A news story from Northern Arizona University about a 2020 study used those words, because tuatara fossils about 150 million years old look very much like tuatara today.

Not every scientist likes the name. Animal Diversity Web points out that tuatara have their own new features, so they are not unchanged leftovers. In the 2020 study, scientists worked with the Māori tribe Ngātiwai to read the tuatara's genes for the first time.

The label "living fossil" is used, and disputed. Northern Arizona University's report on the 2020 Nature genome study described the tuatara that way, noting fossils about 150 million years old that look like living animals; Animal Diversity Web argues the term is misleading because the tuatara, though similar to its extinct relatives, has evolved features of its own.

The genome project, led by Neil Gemmell of the University of Otago in partnership with the Ngātiwai tribe, found a genome of about 5 billion bases, 67 percent larger than the human genome, a slow rate of molecular change, and more genes linked to protection against ageing than in any other vertebrate examined so far.